Ovary

General

WHO classification



Topic Completed: 19 July 2021

Minor changes: 19 July 2021

Copyright: 2003-2021, PathologyOutlines.com, Inc.

PubMed Search: Ovarian neoplasms WHO classification review[PT]

Laura Adhikari, M.D.
Lewis A. Hassell, M.D.
Page views in 2020: 18,121
Page views in 2021 to date: 18,159
Cite this page: Adhikari L, Hassell LA. WHO classification. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorwhoclassif.html. Accessed October 23rd, 2021.
Definition / general
  • This topic covers tumors of ovarian origin (primary) only, with most tumors falling under the categories of epithelial, mesenchymal, sex cord stromal and germ cell
  • The remaining (exceptionally rare) tumors are in the miscellaneous category
Major updates
  • WHO first classified low and high grade serous carcinoma as different subtypes of the same tumor; now it is evident that these are 2 different types of carcinoma with different molecular characteristics, immunohistochemical profile, morphology, pathogenesis and tumor progression
  • Most high grade serous carcinomas of the ovary arise from the distal fimbria of the fallopian tube from a precursor lesion known as serous tubal intraepithelial carcinoma (STIC) (Pathology 2015;47:423, Mod Pathol 2015;28:1101)
  • Low grade serous carcinomas of the ovary arise from benign or borderline serous neoplasms
  • SET (solid, endometrial-like, transitional) patterns harbor p53 mutations and are now under the category of high grade serous carcinoma
  • Many mutations have been found in sex cord stromal tumors and can differentiate subtypes, such as adult granulosa cell tumor (FOXL2) from poorly differentiated Sertoli-Leydig cell tumors (DICER1) and microcystic stromal tumor (CTNNB1 or APC mutation) (N Engl J Med 2009;360:2719, Am J Surg Pathol 2017;41:1178, Genes Chromosomes Cancer 2015;54:353)
  • Small cell carcinoma of hypercalcemic type is associated with SMARCA4 mutations (Histopathology 2016;69:727)
  • Seromucinous carcinoma has been removed and is now a subtype of endometrioid carcinoma (Am J Surg Pathol 2015;39:983)
  • Gynandroblastoma has been reintroduced after being removed from the previous WHO edition
WHO (2020)
Epithelial tumors
Mesenchymal tumors
Mixed epithelial and mesenchymal tumors
Sex cord stromal tumors
Germ cell tumors
Miscellaneous tumors
Tumor-like lesions
Microscopic (histologic) images

Contributed by Lewis A. Hassell, M.D.
Serous borderline tumor

Serous borderline tumor

Serous borderline tumor, micropapillary type

Serous
borderline tumor,
micropapillary
type

High grade serous carcinoma

High grade serous carcinoma

Clear cell carcinoma, ovary

Clear cell carcinoma, ovary

Clear cell adenofibroma, borderline

Clear cell adenofibroma, borderline


Seromucinous borderline tumor

Seromucinous borderline tumor

Dedifferentiated carcinoma in ovary

Dedifferentiated carcinoma in ovary

Sclerosing stromal tumor

Sclerosing stromal tumor

Steroid cell tumor, ovary

Steroid cell tumor, ovary

Granulosa cell tumor, adult type

Granulosa cell tumor, adult type


Sex cord tumor with annular tubules

Sex cord tumor with annular tubules

Reteform Sertoli-Leydig tumor

Retiform Sertoli-Leydig tumor

Sertoli-Leydig tumor, intermediate

Sertoli-Leydig tumor, intermediate

Mixed germ cell tumor

Mixed germ cell tumor

Immature teratoma

Immature teratoma

Board review style question #1
The WHO 2020 classification of ovarian tumors defines benign, borderline and malignant versions of which of the following tumor types?

  1. Brenner tumors
  2. Endometrial stromal tumors
  3. Granulosa cell tumors
  4. Mesonephric tumors
  5. Seromucinous tumors
Board review style answer #1
A. Brenner tumors are classified into 3 groups: benign, borderline and malignant. Malignant seromucinous tumors were removed from WHO 2019. The other tumors do not include these separations.

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Reference: Ovary - WHO classification
Board review style question #2

This histologic pattern would be most commonly expected in which of the following ovarian tumors listed in WHO 2020?

  1. Clear cell carcinoma
  2. Granulosa cell tumor
  3. Sertoli-Leydig tumor
  4. Sex cord tumor with annular tubules
  5. Steroid cell tumor
Board review style answer #2
D. Sex cord tumor with annular tubules is characterized by cells with clear cytoplasm, basal nuclei and eosinophilic tubular material resembling basement membrane. The cells sometimes resemble Sertoli cells and the eosinophilic tubular material can mimic Call-Exner bodies of granulosa cell tumors.

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Reference: Ovary - WHO classification
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